a little help with autofocus and my d5100

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Christina Rotondo

New member
hello everyone! newbie here..

so i have a d5100 and have had for a couple of years. I mainly use it for my youtube videos - but im having a general problem with my autofocus.

focusing is fine when its manual and i have full control, or its in my hand and i am using the autofocus feature because of course I can see what is in focus. however, on a tripod and attempting to focus is another matter. sometimes the autofocus is fine and i'll leave it on and it'll autofocus throughout the video but mainly focus on where I want it to go - okay, fine.
but a lot of the time when I am the subject of the video, it'll focus on the background, or something behind me, and i'll be ever so slightly out of focus which is really frustrating after a long take of a video!

I do have a (cheap) remote i picked up on ebay, but as far as I am aware, i can't focus for video with this as it just takes a photo.
any help or advice would really be appreciated, as its something ive been struggling with for a while.

(also, getting someone to stand in shot isnt always the best and/or most appropriate option. often i film my videos alone and need them done quickly and efficiently.)
thank you!
 
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Don Kuykendall_RIP

RIP :(
Are you stationary when you are doing these video? IF so pre-focus on the spot where you are and leave it on manual. Manuel is better since on the D5100 the auto-focus motor can be heard on the video.
 
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Christina Rotondo

New member
Don Kuykendall said:
Are you stationary when you are doing these video? IF so pre-focus on the spot where you are and leave it on manual. Manuel is better since on the D5100 the auto-focus motor can be heard on the video.
Click to expand...

hey don
i am stationary, but i find that even when i focus on the area i'll be standing in, it wont 100% focus on the exact place i want sometimes, or i think ive focused it and it turns out its ever so slightly out, and when i go to record the viewfinder is too far away for me to notice.

also if it is put onto autofocus , itll autofocus on someting when the camera is initially turned on and then after that first focus it just kind of stops. the square outline in the viewfinder turns red rather than green - waht does this mean?
sometimes its great and autofocuses like crazy, but other times it just stops!
 
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yauman

Senior Member
First Lesson in Videography - Do NOT USE AUTOFOCUS.

Ok.. when it comes to video, here's the mantra - repeat after me... Turn OFF Autofocus... Turn OFF Autofocus ... Turn OFF Autofocus..
Yes, please turn off autofocus - you cannot get away with using autofocus if you want your videos to not look like amateurish vacation videos. Even $100K Studio Video Cameras do NOT have autofocus because autofocus cannot be used for videos - so there's nothing wrong with your D5100. Just turn off the Autofocus when you are in video mode.

If you are videoing a stationary scene, the trick is to have a small aperture, thus increasing the depth of field. If say you are videoing 3 persons seated in line, you need to focus on the center person then set the depth of field so that the persons on either side are in focus. Better solution is to have the people sit in a slightly curved arc arrangement so that all the subjects are at equi-distance from the camera. Hope that makes sense. What this all means is that you need lots of light - lots of bright lights because with a small aperture to get huge depth of field, you will need to really light the subjects. Now you understand why there are so much hot lights in studios!

Now, with say 3 people, if you use auto-focus and locked in on the center person, if that persons head moves (people don't stay still when they talk, they bob their heads and turn their necks!), the autofocus will have to hunt - and if it picks up an object in the background, it will lock to it- now your subjects are out of focus. So, DO NOT USE autofocus when you video.

What about when you are videoing a subject that is moving - that's when you need to get a gadget call "follow focus" - to let you do a dry walk thru and then mark your focus points (literally with a marker or a paper clip) and when when you record, you can rotate the focus ring and not have to guess. "Follow Focus" comes in many different varieties, from cheap to really sophisticated rigs but that are all MANUAL Focus aids. Do NOT use AutoFocus!

I've attached some photos of follow focus rigs. Hope this helps.

SimpleFollowFocus2.jpgSimpleFollowFocus.jpgDSLRVideoFocusing.jpg
 
C

Christina Rotondo

New member
yauman said:
First Lesson in Videography - Do NOT USE AUTOFOCUS.

Ok.. when it comes to video, here's the mantra - repeat after me... Turn OFF Autofocus... Turn OFF Autofocus ... Turn OFF Autofocus..
Yes, please turn off autofocus - you cannot get away with using autofocus if you want your videos to not look like amateurish vacation videos. Even $100K Studio Video Cameras do NOT have autofocus because autofocus cannot be used for videos - so there's nothing wrong with your D5100. Just turn off the Autofocus when you are in video mode.

If you are videoing a stationary scene, the trick is to have a small aperture, thus increasing the depth of field. If say you are videoing 3 persons seated in line, you need to focus on the center person then set the depth of field so that the persons on either side are in focus. Better solution is to have the people sit in a slightly curved arc arrangement so that all the subjects are at equi-distance from the camera. Hope that makes sense. What this all means is that you need lots of light - lots of bright lights because with a small aperture to get huge depth of field, you will need to really light the subjects. Now you understand why there are so much hot lights in studios!

Now, with say 3 people, if you use auto-focus and locked in on the center person, if that persons head moves (people don't stay still when they talk, they bob their heads and turn their necks!), the autofocus will have to hunt - and if it picks up an object in the background, it will lock to it- now your subjects are out of focus. So, DO NOT USE autofocus when you video.

What about when you are videoing a subject that is moving - that's when you need to get a gadget call "follow focus" - to let you do a dry walk thru and then mark your focus points (literally with a marker or a paper clip) and when when you record, you can rotate the focus ring and not have to guess. "Follow Focus" comes in many different varieties, from cheap to really sophisticated rigs but that are all MANUAL Focus aids. Do NOT use AutoFocus!

I've attached some photos of follow focus rigs. Hope this helps.

View attachment 118888View attachment 118889View attachment 118890
Click to expand...

Thank you - really helpful!
and dont worry - i know that autofocus is a nono haha! but desperate times called for desperate measures. I also have a REAALLLYYYY bad thing to admit... so i dont use the manual settings much! I KNOW, its awful. but ive never really taken the time to actually set the aperture and then the white balance and make it look perfect - I really need to do this. what would you recommend a (rough) aperture should be for an indoor bedroom scene? sometimes if filmed in the eveing with low lighting too ?

also could you recommend any settings / how to focus if it is JUST me being in the centre of the focus - as that is all it will ever be when filming my youtube videos with a tripod. how do i ensure that my face is entirely in focus when i return to shot? thank you!
 
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yauman

Senior Member
If you are just doing youtube videos, I would NOT recommend using a sophisticated camera like the D5100. There are cheap cameras made for doing web videos like this Logitech webcam. These cameras are made for what you are doing - they all have very small aperture, huge depth of field and make small images with high sensitivity sensors - just for the web/youtube.

Since you already started with the Nikon let's see how you continue.

The Depth of Field is set by the aperture but it's not a fixed thing - it depends on the focal length of the lens you are using and how far the subject is from the camera. The long the focal length - the shallower DOF ie if you are using a 200mm lens, you'll get a shallower DOF than a 35mm lens for the same aperture setting. Also, using the same focal length and the same aperture, you'll get a shallower DOF if you are 2 feet from the camera than if you are 20 feet.

So, the answer is use the smallest aperture you can get away with for the lighting condition and lens you are using. Since you are videoing with a modern DSLR, make use of the fact that you can crank up the ISO and with the video being used on Youtube, it can be quite small so ISO grains won't show up.

Try this - assuming that you are using a 50mm and sitting about 5-6 ft away from the camera. Set the aperture to F8 or even F11. Set fps to as low as you can without motion blur or jerky looking video. Light yourself as bright as you can now crank up the ISO to whatever is required to get a good looking well exposed video. You just have to do it trial and error method with the ISO and FPS setting to get the right exposure. At F11 with a 50mm lens your face should be in focus even if you move a foot or so either way.

Have fun!
 
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